Gravimetric Reconstruction of the Citlaltépetl-Teteltzingo Volcanic Complex at 32 ka

Abstract

The remaining fault scarps of a collapsed structure at 32 ka, named Tetelzingo crater, that included Citlaltépetl (CT) volcano, and the associated gravity field, are the basis of a reconstruction of the structures involved. The gravity field is obtained from the GGMplus model, from which 3D inversions at resolutions of 1000, 500, and 250 m are performed. Low-gravity anomalies are associated with Sierra Negra (4580 m) and Citlaltépetl (5521 m) volcanoes, as well as with the Chichimeco Dome Complex (~4000 m) (CDC). They are located within a SW-NE anomaly that serves as a constraint to the reconstruction. The associated Bouguer anomaly appears as a continuous low-gravity surface; however, its vertical derivative Dz shows that the sources of those three structures are separated. The fault scarps are complemented with inferred trajectories that suggest the existence of two volcanoes before the collapse at 32 ka: Citlaltépetl and the Ancestral Teteltzingo. Density cross-sections identify three stratified magmatic deposits under the summit of CT. On the summit of CT, there is an anomalous concentration of high-density materials, attributed to the presence of domes and lava flows, which mask the position of the volcano’s chimney. The existence of the Ancestral Teteltzingo volcano (ATE) is inferred NE of CT from the associated density distribution; CDC is at the center of the ATE structure and is interpreted as a resurgent activity at <8 ka. Sierra Negra volcano (SN) shows low-density distributions in and around its summit, contradicting the idea that this is an extinct volcano.